Two temperature refrigerating apparatus



O 1955 J. w. JACOBS TWO TEMPERATURE REFRIGERATING APPARATUS Filed Dec.13, 1952 INVENTOR. James W Jacobs United States Patent TWO TEMPERATUREREFRIGERATING APPARATUS James W. Jacobs, Dayton, Ohio, assignor toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareApplication December 13, 1952, Serial No. 325,813

6 Claims. (Cl. 62117.3)

This invention relates to refrigerating apparatus and particularly to aprimary refrigerating system having a closed secondary refrigeratingsystem associated therewith and rendered effective thereby.

An object of my invention is to provide a double refrigerating systemwherein the temperature of the evaporating portion of a closed secondaryrefrigerating system associated with a primary refrigerating system isintermittently and successively varied over a relatively widetemperature range.

Another object of my invention is to provide a closed secondaryrefrigerating system with a siphoning means or device which is renderedeffective automatically by refrigerant in the system to cause theevaporating portion thereof to at one time attain a temperature belowfreezing and at another time to be increased to a temperature abovefreezing.

A further object of my invention is to provide means rendered efiectiveautomatically by refrigerant contained in a closed secondaryrefrigerating system associated with a primary refrigerating systemtocause the evaporating portion of the secondary system to intermittentlyand successively function at a temperature whereby frost or ice willaccumulate thereon and at a higher temperature to defrost the frost orice therefrom.

It is a still further and more specific object of my invention toprovide means for defrosting the evaporator utilized to cool theinterior of an unfrozen food storage compartment of a refrigeratorcabinet on which frost normally accumulates while maintaining theevaporator employed to cool a frozen food storage compartment in thecabinet below freezing at all times.

Other objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing, wherein a preferred form of the present invention is clearlyshown.

The figure in the drawing is a perspective view showing somewhatdiagramatically a refrigerator constructed in accordance with myinvention and having parts thereof broken away.

Referring now to the drawing, reference numeral 10 designates the outershell of a refrigerator cabinet having a metal liner 11 forming afreezing or frozen food storage compartment 12 and another metal liner13 forming a main or unfrozen food storage compartment 14 therein.Suitable insulating material 16, interposed between shell 10 and theliners 11 and 13, surrounds the compartments and isolates one from theother. The refrigerator is of the multiple door type wherein a firstdoor 17 is provided for closing the front opening to the freezing orfrozen food compartment 12 and a second door 18 is provided for closingthe front opening of the unfrozen food compartment 14. The invention isnot restricted to the specific type of cabinet disclosed since it isequally applicable to a refrigerator in which a single door closes bothcompartments.

A primary refrigerating system is associated with the refrigeratorcabinet 10 and includes a refrigerant translat- "ice ing unit comprisinga motor-compressor (not shown), a condenser 21 and an evaporator 22.Evaporator 22 may be in the form of refrigerant expansion conduit loopswrapped around and secured to the outer surface of liner 11 formaintaining the frozen food compartment 12 at a below freezingtemperature. The condenser 21 is supported in a lower machinecompartment in the cabinet 10 below main food compartment 14 for apurpose to be hereinafter described. Motor-compressor unit of theprimary refrigerating system may be cyclically operated in response totemperatures prevailing in compartment 12 by a thermostatically actuatedelectric switch as is usual or conventional in the art. A closedsecondary refrigerating system is also associated with cabinet 10 andfunctions or is rendered effective by the refrigerating effect producedby the primary refrigerating means or evaporator 22. This secondarysystem includes a refrigerant condensing portion or conduit 26 disposedin intimate heat exchange relationship with the primary evaporator 22.The secondary system also includes a refrigerant evaporating portion inthe form of conduit passages 27 provided in superimposed and weldedtogether sheet metal plates as is now conventional in the art. Platesecondary evaporator 27 is mounted, in any suitable or desirable manner,within the main unfrozen food storage compartment 14 and exposed to theair therein. A pipe or conduit 28 connects the outlet of passages 27with the condensing conduit portion 26 of the secondary refrigeratingsystem. A restricting means in the form of a small diametered pipe orconduit 29 connects the outlet of refrigerant condensing conduit portion26 of the secondary system with a tank 31 disposed in the insulatingmaterial 16 of cabinet 10. Another pipe or conduit 32 is connected tothe inlet of the passages 27 of secondary plate evaporator and entersthe tank 31 at a substantial distance above the bottom thereof. The openend of pipe 32 is disposed near the bottom of tank 31. The arrangementof pipe 32 and the disposition of its open end, communicating with theinterior of tank 31, forms a siphoning means or device in the closedcircuit of the secondary refrigerating system intermediate therefrigerant condensing portion 26 and the refrigerant evaporatingportion 27 thereof and is rendered effective automatically byrefrigerant in this system in a manner and for a purpose to be presentlydescribed.

A trough 36 is provided directly beneath the secondary plate evaporatorportion 27 and serves to direct water dripping therefrom down along awall of compartment 14 whereby the water will flow into a drain opening37 provided in the bottom wall of compartment 14. The drain opening 37discharges the water into a condensate evaporating pan 33 mounted uponthe refrigerant condenser 21 of the primary refrigerating system. Pan 38is preferably in intimate heat exchange relationship with condenser 21so that heat generated by this condenser will cause water in pan 38 tobe vaporized into the condenser air stream. Such disposal of condensatewater is now well known to those skilled in the art.

As before stated the evaporator 22 of the primary refrigerating systemis adapted to maintain the interior of frozen food compartment 12 at asubstantially constant low temperature, say for example, between 5 and15 F. The secondary refrigerating system is calibrated and associatedwith the primary refrigerating system in such a way as to cause theevaporating portion or plate 27 thereof to at times fall below freezingtemperature. The below freezing temperature of secondary evaporatingportion 27 causes the same to withdraw moisture from the air incompartment 14 and deposit this moisture upon the same in the form offrost or ice. In accordance with my invention it is desired to providean automatic defrost cycle in the operation of the secondaryrefrigerating system in order to clear frost or ice from evaporator 27and render this evaporator more efiicient in cooling compartment 14. Inorder to intermittently and successively cause automatic defrost cyclesfor the refrigerant evaporating portion of the seeondary system Iprovide this system with a quantity: of refrigerant slightly greaterthan the capacity of the trapping} tank or siphoning device 31.

When the refrigerator is placed in operation to reduce the temperatureof the primary evaporator to between the temperature limits given, forexample, refrigerant contained in the, secondary refrigerating systemevaporates in portion .26 of the secondary system flows therefrom intotanle31-through the restricting tube or pipe 29.. This liquidrefrigerant slowly drains into the siphon tank 31 wherein it temporarilytrapped. Finally the evaporating portion or plate 27 is starved ofliquid refrigerant'and its temperature begins to rise. This evaporatingportion 271 of the secondary system rises in temperature above freezingbefore the siphoning means is rendered effective and frost or ice on thesecondary evaporator melts therefrom then flows, by way of trough 36 anddrain opening 37, into the defrost water'evaporating pan 38. Shortly'after the temperature of secondary evaporator 27 has risen abovefreezing the liquid level of refrigerant trapped and accumulating insiphoning tank 31 increases to a point above the uppermost part ofconduit or pipe 32. This increase in the level of refrigerant in tank 31renders the siphoning device operative. 7 contains a predeterminedamount of liquid refrigerant prior to rendering the siphoning meansoperative and an increase of more than this predetermined accumulationof liquid refrigerant therein thus renders the siphoning deviceeifecti've automatically for substantially emptying liquid refrigerantfrom tank 31 and quickly dumping the same into the evaporating portion27 of the secondary refrigerating system. This evaporating portion ofthe secondary' refrigerating system again functions to produce a belowfreezing temperature thereof. Liquid refrigerant dumped into evaporator27 absorbs heat from compartment 14:, evaporates and recondenses in thecondenser 26 to thus start another cycle of intermittent and successivecycles'of above freezing and below freezing temperatures of thesecondary evaporator to periodically clear frost or ice therefrom.

It should be apparent from the foregoing that I have provided a novelapparatus for and method of intermittently and successively defrostingthe evaporator of a secondary refrigerating system. I accomplish thisdesideratum without employment of moving parts, since the siphoningdevice isYrend-ered effective automatically by refrigerant in thesystem, and therefore retain the secondary refrigerating system in assimple and inexpensive form as is possible. My invention provides forthe defrosting of the refrigerant evaporating portion of a secondaryrefrigerating system without materially increasing the temperature'ofthe cooling means or evaporator of a primary refrigerating systemassociated therewith and utilized to renderthe same operative. Thus animproved refrigerator of the type having a substantially constant Tank31 holds or.

a closed secondary refrigerating system containing a volatilerefrigerant and including a refrigerant condensing portion in heatexchange relationship with said primary evaporator, a refrigerantevaporating portion, a conduit for conveying refrigerant evaporated insaid evaporating portion into said condensing portion and meansinterposed between said portions for conveying refrigerant liquefied insaid condensing portion into said evaporating portion and for causingsaid evaporating'portion to produce a temperature below 32 F. and above32 F. alternatively, said means comprising a siphoning device and afixed restrictor for restricting'flow of liquid refrigerant from thecondensing'portion of said secondary system into said siphoning device,said siphoning device receiving a predetermined amount of liquidrefrigerant from said condensing portion of the secondary system andtrapping the same therein, said siphoning device being renderedeffective in response. to an aeeuninlt-ion of more than saidpredetermined amount of liquid refrigerant'therein for dumpingsubstan't'iallyall of said trapped liquid refrigerant into theevaporating portion of said seeondary system whereby its temperaturefalls below 32 F. and moisture deposits thereon in the form of frost orice, and said restrictor delaying the aceuniulation of said more thansaid predetermined amount of liquid refrigerant in said siphoning devicewhereby the temperature of said evaporating portion of the secondaryrefrigerating system rises above 32" F. for defrosting the frost or icetherefrom.

2-. In c m I storage eornp tr'nent within said cabinet, a primaryrefrigeratirig system associated with said cabinet including arefrigerant translating unit and a freezing evaporator for cooling saidfrozen food compartment, an unfrozen food storage compartment withinsaid cabinet, a closed secondchange relationship with said primaryevaporator, a re-;'

frigeraiit evaporating portion disposed within said unfrozen foodeomparftniefnt and exposed to air therein for cooling same, a conduitfor conveying refrigerant evaporated in' said e ,a ting portion intosaid condensing portion and means interposed between'said portions. forconveying refrigerant liquefied in said condensing portion into saidevaporating ortion and for causing said evapora' tion portion to prof uca} temperature below 32 F. and above 32 F. alt rnat ively, said meanscomprising a si ho ing devit'l a'rida fixed restrietor for restrictingflow of liquid refrigerant from the condensing portion of said secondarysystem into said siphoning device, said siphoningdevice receiving apredetermined amountof liquid refrigerant from Said condensing portionof the secondary system and trapping the same therein, said siphoningdevice b'eing' r'en ered effective automatically in response to anaccumulati of more than said predetermined amount of liquid refrige ve'rein for dumping substantially all of said trapped liquid refrigerantinto the evaporating portion of said secondary system whereby itstemperature falls below 32 F. and moisture is withdrawn from air in saidunfrozen food ompartm nt and deposits thereon in the form of frost orie'e, and said restrictor delaying the aCClb mnlatiorr of said rnor"than said predetermined amount of refrigerant in sa d sip ning devicewhereby the temperature of said evaporating, portion of the secondaryrefrigerrating system" rises above 32 F. fol-defrosting the frost or icetherefrom, a

3. The combination defined in claim 2 whereina means.

is provided to eonvey the defrost water out of the unfrozen food storagecompartment.

4. In combination, a primary refrigerating system in:

l n re r e ant tr nsla ing unit and an eva ora o a ation, arefrigerat'or cabinet, a frozen food perature below and above 32 B, saidmeans comprising an insulated unheated siphoning device interposed inthe secondary system between saidv condensing and said evaporatingportions thereof, said siphoning device receiving a part of the totalamount of refrigerant in said secondary system from the condensingportion thereof and trapping the same up to a predetermined leveltherein, said siphoning device being rendered effective solely by anincrease in the level of refrigerant received therein from the remainderof the amount thereof in said secondary system, above said predeterminedlevel for substantially emptying the trapped refrigerant therefrom andsimultaneously feeding all of the same into said evaporating portionwhereby its temperature falls below freezing and moisture depositsthereon in the form of frost or ice, and said siphoning device beinginefiective for feeding refrigerant into said evaporating portion of thesecondary refrigerating system during accumulation of refrigeranttherein up to said predetermined level whereby the temperature of saidevaporating portion rises above freezing and defrosts the frost or icetherefrom.

5. In combination, a refrigerator cabinet, a frozen food storagecompartment within said cabinet, a primary refrigerating systemassociated with said cabinet including a refrigerant translating unitand a freezing evaporator for cooling said frozen food compartment, anunfrozen food storage compartment within said cabinet, insulatingmaterial around and between said compartments, a closed secondaryrefrigerating system having a refrigerant condensing portion in heatexchange relationship with said primary freezing evaporator and arefrigerant evaporating portion disposed Within said unfrozen foodcompartment and exposed to air therein for cooling same, means forcausing said evaporating portion of the secondary refrigerating systemto alternatively produce a temperature below and above 32 F., said meanscomprising an unheated siphoning device interposed between saidcondensing portion and said evaporating portions of the secondaryrefrigerating system and surrounded by said insulating material, saidsiphoning device receiving a part of the total amount of refrigerant insaid secondary system from the condensing portion thereof and trappingthe same up to a predetermined level therein, said siphoning devicebeing rendered effective solely by an increase in the level ofrefrigerant received therein, from the remainder of the amount thereofin said secondary system, above said predetermined level forsubstantially emptying the trapped refrigerant therefrom andsimultaneously feeding all of the same into said evaporating portionwhereby its temperature falls below freezing and moisture is Withdrawnfrom air in said unfrozen compartment and deposits thereon in the formof frost or ice, and said siphoning device being ineffective for feedingrefrigerant into said evaporating portion of the secondary refrigeratingsystem during accumulation of refrigerant therein up to saidpredetermined level whereby the temperature of said evaporating portionrises above freezing and defrosts the frost or ice therefrom.

6. The combination defined in claim 5 wherein a drain opening isprovided in the unfrozen food storage compartment for conveying thedefrost water out of the same.

References Cited in the file of this patent UNITED STATES PATENTS

